Heretofore there have been proposed successive screw feeder drivers capable of successively feeding and driving screws into a plate such as a wooden plate, a metallic plate, or a plaster board to fix the plate to a floor surface or a wall surface. For example, a conventional successive screw feeder driver of this type is shown in FIG. 18. In this conventional successive screw feeder driver, which is indicated at 101, a drive unit 104 is mounted within a screw driving mechanism body 103 having a grip handle 102, and a screw feed mechanism body 106 is attached to the screw driving mechanism body 103 through a support member 105 so as to be slidable in the screw feeding and driving direction which is the longitudinal direction. In the successive screw feeder driver 101, each screw S is rotated with a rod-like screw driving bit 107 corresponding to a screwdriver as a commonly-used tool. As soon as the screw S is driven into the surface of a plate, the screw feed mechanism body 106 moves back slowly toward the screw driving mechanism body 103 (in the direction of arrow X), and when the nose end of the bit 107 and the front end of the screw feed mechanism body 106 assume substantially the same position, the screw S driving operation is over.
In the successive screw feeder driver 101, as shown in FIG. 19, a large number of screws S, S, . . . are arranged in a line on a belt-like member of a screw strip S1, the belt-like member being formed of a synthetic resin. The screw strip S1 is received in a spiral form into a magazine 108 which is generally cylindrical. In an interlock with a screw feeding operation performed in the screw feed mechanism body 106 the screw strip S1 is advanced to a screw driving position. When the successive screw feeder driver 101 is to be used, the drive unit 104 mounted within the screw driving mechanism body 103 is started to rotate by depressing a trigger switch 109 corresponding to the forefinger position of a grip handle 102, causing the bit 107 to rotate through a reduction mechanism 110 and a clutch 111. The nose end of the bit 107 thus rotated comes into abutment against the head portion of a screw S positioned at the front end of the screw strip which has been loaded into the screw feed mechanism body 106.
The screw S is driven into the surface of a workpiece such as a plate by the rotating motion of the bit 107. The magazine 108 which receives therein the screw strip S1 in a coil form is attached removably to a side face of the screw driving mechanism body 103. The screw strip S1 accommodated within the magazine 108 is withdrawn from an outlet 112 of the magazine 108 and is loaded into the screw feed mechanism body 106 while being bent at an angle of about 90.degree. relative to the strip withdrawing direction.
One such conventional successive screw feeder driver 101 permits the use of plural types of screws different in length so long as the difference in length of the screws falls within a certain operationally allowable range. However, to use screws, longer than that range requires the use of multiple screw feed drivers. Thus, the allowable range of screw length in one successive screw feeder driver is narrow. Dedicated successive screw feeder drivers 101 are required for short and long screws, respectively. In other words, a plurality of successive screw feeder drivers 101 are needed.
If the magazine 108 for receiving the screw strip S1 therein has a large depth, it can accommodate both the long and the short screws S. However, if extremely short screws S are accommodated in the magazine 108 having a large depth, there is a fear that the screw strip S1 which is in a coil form may get entangled within the magazine 108 and become unable to be withdrawn in a satisfactory manner. Besides, since the magazine 108 is attached to a side face of the successive screw feeder driver 101, the distance from the magazine 108 to the screw feed mechanism body 106 is long, and the outlet direction of the magazine 108 and the advancing direction of the screw strip S1 in the screw feed mechanism body 106 are not the same, so that the screw strip S1 is twisted as it is fed to the screw feed mechanism body 106, resulting in the operation thereof becoming unstable. Further, when the quantity of screws on the screw strip S1 becomes small, an end portion of the screw strip will jump out from the magazine, with the result that the screw strip S1 and the screws S become loose and are apt to damage a floor surface or a wall surface.
When the conventional successive screw feeder driver 101 is to be used for a floor surface, an operator thereof is required to operate the feeder driver 101 in a half-sitting posture or on his or her bended knees. In the case the screw driving operation continues over a long time, fatigue of the operator is apt to accumulate. Under the circumstances, it has been desired to develop a successive screw feeder driver which permits the operator to be standing up during the screw driving operation. Further, every time the screw driving operation is over, the operator is required to throw down the successive screw feeder driver 101 sideways and place it on a floor surface or the like, while when the screw driving operation is to be again started, the operator must lift the feeder driver 101. Thus, it is not easy to handle the successive screw feeder driver which is heavy.
The present invention has been accomplished in view of the above-mentioned problems and it is an object of the invention to provide a successive screw feeder driver employable at different mounting positions of a belt-like member of a screw strip and hence permitting the use of plural types of screws different in length, and further capable of accommodating even extremely short screws in a magazine without causing entanglement of the screws in the magazine.